The present invention relates to a treatment tool for an endoscope.
Among various kinds of treatment tools for an endoscope, there is known a rod-shaped treatment piece such as a high frequency incision tool with a rod-shaped electrode provided to be pulled in and pushed out from a distal end of a flexible sheath. The rod-shaped treatment piece is configured to be ejected forward from (and inserted backward into) the distal end of the flexible sheath by operating an operation wire arranged to be movable back and forth along an axis line thereof in the flexible sheath (for example, U.S. Patent Application Publication No. 2005/0215853).
According to the aforementioned high frequency incision tool for the endoscope, it is required to appropriately adjust a length of a projecting portion of the rod-shaped electrode depending on a state of a biomedical tissue to be incised. To meet the requirement, the rod-shaped electrode is monitored on an observation window so that the length of the projecting portion thereof can be checked.
However, as shown in FIG. 17, when the rod-shaped electrode 92 is viewed from an observation port 91 of the endoscope, the rod-shaped electrode 92 is partially hidden by the flexible sheath 93 with a diameter larger than that of the rod-shaped electrode 92. Namely, as shown in FIG. 18, a part beyond a predetermined projection length of a portion projecting from the distal end of the flexible sheath 93 can only be monitored through the observation port 91 of the endoscope. Consequently, it is impossible to check an accurate length of the portion of the rod-shaped electrode 92 that projects from the distal end of the flexible sheath 93.
In addition, as shown in FIG. 19, in a state where the high frequency incision tool 90 for the endoscope projects from the endoscope by more than a predetermined length, the rod-shaped electrode 92 is completely hidden by the flexible sheath 93. Hence, as shown in FIG. 20, the rod-shaped electrode 92 cannot at all be observed on the observation window of the endoscope, and thereby an endoscopic treatment such as high frequency incision might not safely be implemented.